Effects of some polycyclic aromatic hydrocarbons on the natural population of marine bacterioplankton

Doubling rate, production and the daily P/B ratios of natural bacterioplankton populations of the Gulf of Riga were estimated under the impact of 0.001 mg/dm3 anthracene and phenanthrene. In many cases, reduction in the total number of microorganisms was observed, coupled with a decrease in bacterial production. Studies on 24 h exposure to anthracene and phenanthrene demonstrated toxicity of the hydrocarbon concentrations used to the microbial communities of the Gulf of Riga.